[rmcpherson]

The article mentions that plastic bags work better than emergency "space" blankets since they block moisture and thus evaporative cooling. A large industrial trash bag is part of my emergency supplies on cold backpacking trips. It's cheap, weighs almost nothing, and provides protection from both radiative and convective cooling.

[rconti]

Funny, this Californian ran a half marathon in northern norway rain (during the summer, though, so it was about 45f). I inadvertently tested this plastic bag theory.

My luggage had been lost by the airlines, so I didn't have my rain shell, just the most basic running clothes that I wisely chose to put in my carryon.

I ended up running the race in t-shirt and shorts covered by a free plastic poncho handed out by a restaurant. I quickly saturated my clothes from a combination of sweat and rain getting in, but it functioned like a wet suit in that it prevented the fresh rain and wind from cooling me evaporatively, while my body kept my wet clothes warm.

While it was a bit stuffy, I was afraid I'd get cold very quickly in the wind and rain if I took it off (which I did in the last few miles, and yes, it got cold quickly). As soon as I stopped running, even with a space blanket, even going indoors, my temperature plummeted EXTREMELY rapidly.

At 45f in the dry I'd typically use long sleeves (and I repeated this experiment this past weekend in Napa) although, again, it's really just to keep you warm while you wait to start; once you're running, it's no problem to get by with only short sleeves and shorts.

[jniedrauer]

Related: I used ziploc bags as vapor barriers nested between two pairs of socks while on a multi-month winter hiking trip in trail shoes. It was extremely effective. I could posthole in deep snow all day in my running shoes and not get frostbite.

[klondike_klive]

How did you avoid damp-related problems like fungal overgrowth?

[jniedrauer]

It didn't end up being a problem. I washed my feet when I could, used thick wool socks, let my feet air out at camp, and that was enough.

[krsdcbl]

The article distinguishes it as a better option _when wet_

[js2]

I'm surprised. I've lined up before races in the cold and I've found an emergency blanket keeps me warmer than a trash bag. I've tried both. Neither beats used sweats from Good Will, but that's too much to run with.

[jvm___]

You're supposed to pretend your the garbage and climb into the bag - creating a closed system where you keep the lost water warm.

[chachachoney]

Space blankets are made of mylar, and are not porous.

Not sure why people here think that they don't block moisture and allow evaporative cooling...

https://en.wikipedia.org/wiki/Space_blanket

[oska]

They're not a bag. Thus they're not sealable.